The present invention relates to a portable wheelchair with a simplified frame construction which can be raised to a standing position with a minimal effort from the user.
Wheelchairs which can be raised from a sitting position to a standing position are well known in the art. Some of the wheelchairs require more effort from the user to raise the chair into the standing position. U.S. Pat. No. 4,519,649 to Tanake et al. shows a wheelchair with a gas spring placed in a compressed state when the chair is in the sitting position. When the user desires to raise the chair to the standing position, the compressed gas spring is gradually released to raise the chair. However, the gas spring does not produce all the force needed to raise the person sitting in the chair. Effort on behalf of the user is required in addition to that provided by the gas spring. A person without full upper body strength would not have enough power to raise the chair. The gas spring could be increased in stored power to raise the person without much effort, but then the person would need additional effort to lower the chair to the sitting position in order to overcome the stronger gas spring.
Another device, U.S. Pat. No. 5,108,202 to Smith, makes use of a hydraulic jack to raise the chair to a standing position. A hydraulic jack could be used by a person with limited strength to raise the chair, since the leverage of the input device to the jack could be modified so that little force is required to drive the pumping unit of the jack.
One of the disadvantages of the above wheelchairs, and others in the prior art, is that the chairs use a double frame structure. The frame comprises a left side frame and a right side frame. The sides are connected together by cross members to form the frame structure. Using this double frame structure increases the cost of materials and manufacture of the chair. Also, in a wheel chair which uses a hydraulic jack, the cross members must be strong enough to support the load developed by extending the hydraulic jack. The side members must also be reinforced since the cross members connect to the side members.
Further, the wheelchairs that have raising capabilities do not provide any means by which to notify the user when the chair has reached the raised position in order that the user does not waste additional effort.
The objects of the present invention are to provide a wheelchair with an ability to raise a person to a standing position requiring minimal effort by the user.
Another object of the present invention is to provide a standing assist type wheelchair with the mobility of a normal wheelchair (non-standing assisted type).
Another object of the present invention is to provide a wheelchair which uses a hydraulic jack with a simplified frame construction.
A further object of the present invention is to provide the wheelchair with a device to alert the user when the chair has reached the raised position.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practicing the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention includes a wheelchair having a frame supporting two foot rests, a seat and a back rest of the wheelchair. The frame consists of a single frame extending between the center of the foot rests, the seat and the back rest, and the frame is supported for pivoting or tilting motion by a wheel axle frame section. The first and most preferred embodiment uses a hydraulic system to raise the seat, while a second and third embodiment uses a toggle and ratchet system, and a fixed lever and spring assisted device, respectively. The hydraulic system offers a high mechanical advantage, an integrated lowering system, low maintenance, little user effort to activate the lifting system, and high cost effectiveness.
Another feature of the invention is an electrical buzzer that beeps when the seat has reached its final and upright position so that the user does not continue trying to raise the seat.
According to one aspect of the invention a wheelchair includes a central frame, a wheel frame and a lift. The central frame has a back, a seat and a leg support. The back support is pivotably attached to the seat support and the seat support is pivotably attached to the leg support. The wheel frame has a rear member and two wheels connected thereto. The wheel frame also has a front member and two wheels connect connected thereto. The front member connects to the rear member of the wheel frame. The lift is positioned between the wheel frame and the central frame. A user may operate the lift to move the central frame from a sitting position to a standing position.
According to another aspect of the invention a wheelchair includes a lower frame, an upper frame, a vertical member and a lift. The lower frame is coupled with a plurality of wheels. The upper frame has a back member, a plurality of seat members, and a leg member. The back member pivotably attaches to one end of the plurality of seat members. The leg member pivotably attaches to the opposite end of the plurality of seat members. The vertical member rigidly attaches to the lower frame and pivotably attaches to the plurality of seat members. The vertical member is positioned between the two ends of the seat members. The lift has a bottom and a top. The bottom rests upon the lower frame and the top presses against at least one of the plurality of seat members. The lift is positioned between the vertical member and the end of the plurality of seat members that attaches to the back.
It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.